Climate change deteriorates water quality in the Himalayas

11 Feb 2016

A new study by Lappeenranta University of Technology (LUT) on the climate change and geochemical process of waters and lake sediments on the Tibetan Plateau shows that global warming affects geochemical processes such as glacier melting, soil erosion and sediment release. This deteriorates the water quality of rivers and lakes, thus significantly impacting the lives of 40 per cent of the world's population living in the area.

According to the results, concentrations of mercury, cadmium and lead in high-altitude lake sediments where there is less human activity were significantly higher compared to more populous low-altitude areas. These findings indicate that atmospheric long-range transportation of pollutants in remote areas of the Himalayas might deposit at high altitudes. Precipitation during the monsoon season in the region has a high concentration of nutrients, implying that atmospheric pollution is possibly transported to the Himalayas from South Asia by the India monsoon. This means that human activities in the surrounding area affect the waters of the Tibetan Plateau.

The research also found that arsenic concentrations in rivers in the Southern Tibetan Plateau were higher than the guideline for drinking water set by the World Health Organisation (WHO) due to the existence of thermal springs in the region.

The Tibetan Plateau has an extensive permafrost cover that stores a lot of carbon. The temperature in the area has been increasing for the past 500 years and the climate in the central plateau has been warming more than other in regions over the last century. Rising temperatures export old carbon stores from the ancient permafrost into contemporary rivers in the Tibetan Plateau. Global warming will continue to release more carbon into the water system, which will, in turn, intensify regional climate change and affect water quality.

The Tibetan Plateau is the highest plateau on Earth and also known as the "Third Pole" and "water tower of Asia". Water quality is an essential issue for the inhabitants around the Himalayan area. It is under the threat of climate change and human activity, since the two population-heaviest countries, China and India, are located in the area. However, the local citizens' awareness and understanding of the effects of climate change on water quality and mitigation actions are very limited. The researchers analysed the impacts of climate change on water quality of the lakes, precipitation, as well as headwaters in three major Asian rivers in the Tibetan Plateau: Yangtze River, Yarlung Tsangpo River and Ganges River.

Professor Mika Sillanpää, the principal investigator of the project, calls for urgent research to understand the carbon cycle in the Himalayas:

"Global warming releases increasing amounts of carbon matter from the permafrost into waters and then into the atmosphere. This will intensify both regional and global climate change. It will affect human livelihoods, rangeland degradation, desertification, loss of glaciers and more," Sillanpää says.